This one was astronomically bad but kinda understandable if you were born deaf, dumb and blind and therefore had never played any sort of sport or goal orientated game ever. I was playing Madden 08 with a friend and i've just scored a touchdown so he's seen me use the offensive system. It's his turn and he hikes the ball. He then turns around and runs towards his own end zone as the quarterback all the while yelling that i've got no defence and I suck. He gets to the endzone, drops his control and gives me the double finger. His QB is just sitting in the endzone with the ball while half my team runs up the field towards him. I switch to my linebacker, sprint full on and use the hitstick basically turning his ribcage into confetti. He drops the ball and one of my defensive linesman jumps on it scoring. My friend goes googly-eyed for a second, follows it up with a WTF? and I show him that the one that his viewpoint is facing is the one you're supposed to aim for then I just completely crack up laughing at what an idiot he was.
Another one from CoD4 that I can remember, this is from the same game so it's double the shame. Me and a mate are playing at an internet cafe, doing a couple of SnD rounds waiting for some friends because i'm a sick bastard and I like to see my friends fail and he wanted to because I said that's the game mode that I play in clan scrims. We're on opposite teams and he and one guy are up(this is on Vacant). They manage to get one of my crappier team mates down with him getting the kill and the other guy biting the dust. He then thinks that was the last guy left for some reason that I still can't fathom and starts firing his weapon into the air emptying it of all ammo and does the same with his pistol. What he doesn't realise is that there are still 6 of us up and on my map all these arrows surge towards the orange dot. Obviously i'd pleased the gods in some way because I got to him before anyone else and just ran straight up to him. He spots me, lets out a yell and fires his empty ak at me which clicks. He yells again and switches to his pistol which is also clicks. He starts swearing and starts to just palm the keyboard and by complete accident knifes the air which misses me I then take my deagle out and just 2 shot him in the head. Later on in the game (while I'm spectating while some update gets downloaded for the computer) he's behind a printer or something and spots someone. He pops his head out and tries to throw his grenade but crouches at the same time so he hits the printer in front of him which bounces to rest at his feet. He yells out some expletives and picks up the grenade to throw it away. He manages to hit the only rafter in a patch of about 3x5m square opening in the roof not to mention the rest of the corridor. The grenade bounces back, hits him in the head and explodes killing him. I almost died laughing at this point so we left the game to play something he didn't suck at.